In the printing industry, graphical information such as photographs or artwork can be reproduced by one of several types of printing process. Lithographic printing is one such printing process. In lithographic printing, a lithographic plate is mounted on a lithographic press. The lithographic plate includes a hydrophilic surface on which an image is created using hydrophobic material. A hydrophobic ink is used in printing. The ink is attracted to the hydrophobic image area on the plate and is repelled by the hydrophilic non-imaged area on the lithographic printing plate. The inked image is then used for making lithographic prints. The lithographic printing process is a complex process involving wet chemicals and costly equipment.
Color proofing is an integral part of the printing reproduction process. Color proofs are used to predict the appearance of the final reproduction, to monitor and control the many stages of the image reproduction process, and to check the compatibility of a number of subjects to be printed on the press at the same time. For a color proof to be acceptable to a customer, it is required to be a close simulation of the final printing job. To be acceptable to the printer, the proof must be capable of being produced consistently. The proof must look and preferably feel like the printed job. For this reason, most proofs in the past have been made on printing presses with the same paper and inks to be used on the printed job. The proof sheets are sent to the a selector (a critic for judging images) who determines whether or not their initially selected images are indeed suitable for the desired publication. If the images are not suitable, another round of proof sheets may be generated using different images or different printing parameters. This iterative process can be very costly and time consuming.
In order to reduce the costs of generating proofs, several proof processes have been devised, which include overlay proofs, integral proofs, and digital proofs such as the Kodak Approval system. For example, IRIS Graphics, Inc. (Scitex Co.) has used a continuous ink jet printer to print proof images. In a trade show known as Print'97 in Chicago, the same company demonstrated that a continuous ink jet printer can also be used to produce a lithographic printing plate. In spite of these efforts, however, there remain substantial problems in getting images selected and ready for inclusion in a publication. For example, a proof press still uses a complex and expensive piece of equipment. Additionally, many proof presses often do not duplicate well the final printing job due to the substantial differences in the small proof printing press and the large printing press used for the final production process.
There still exists a need to provide a simplified process and less expensive equipment for making image proofs, lithographic printing plates, flexographic printing plates, graphic arts photomasks, gravure printing cylinders and other graphic arts media.